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                    Recover捕获异常
            
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                    基于指针对象的方法
            
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                    通过嵌入结构体来扩展类型
            
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                    方法值和方法表达式
            
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                    示例: Bit数组
            
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                    封装
            
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                    接口
            
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                    接口是合约
            
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                    接口类型
            
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                    实现接口的条件
            
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                    flag.Value接口
            
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                    接口值
            
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                    sort.Interface接口
            
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                    http.Handler接口
            
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                    error接口
            
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                    示例: 表达式求值
            
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                    类型断言
            
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                    基于类型断言识别错误类型
            
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                    通过类型断言查询接口
            
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                    类型分支
            
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                    示例: 基于标记的XML解码
            
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                    补充几点
            
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                    Goroutines和Channels
            
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                    Goroutines
            
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                    示例: 并发的Clock服务
            
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        <li class="chapter " data-level="1.9.3" data-path="../ch8/ch8-03.html">
            
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                    示例: 并发的Echo服务
            
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                    Channels
            
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                    并发的循环
            
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                    示例: 并发的Web爬虫
            
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                    基于select的多路复用
            
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                    示例: 并发的目录遍历
            
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                    并发的退出
            
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                    示例: 聊天服务
            
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        <li class="chapter " data-level="1.10" data-path="../ch9/ch9.html">
            
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                    基于共享变量的并发
            
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                    竞争条件
            
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                    sync.Mutex互斥锁
            
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        <li class="chapter " data-level="1.10.3" data-path="../ch9/ch9-03.html">
            
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                    sync.RWMutex读写锁
            
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                    内存同步
            
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                    sync.Once惰性初始化
            
                </a>
            

            
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        <li class="chapter " data-level="1.10.6" data-path="../ch9/ch9-06.html">
            
                <a href="../ch9/ch9-06.html">
            
                    
                    竞争条件检测
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.10.7" data-path="../ch9/ch9-07.html">
            
                <a href="../ch9/ch9-07.html">
            
                    
                    示例: 并发的非阻塞缓存
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.10.8" data-path="../ch9/ch9-08.html">
            
                <a href="../ch9/ch9-08.html">
            
                    
                    Goroutines和线程
            
                </a>
            

            
        </li>
    

            </ul>
            
        </li>
    
        <li class="chapter " data-level="1.11" data-path="../ch10/ch10.html">
            
                <a href="../ch10/ch10.html">
            
                    
                    包和工具
            
                </a>
            

            
            <ul class="articles">
                
    
        <li class="chapter " data-level="1.11.1" data-path="../ch10/ch10-01.html">
            
                <a href="../ch10/ch10-01.html">
            
                    
                    包简介
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.11.2" data-path="../ch10/ch10-02.html">
            
                <a href="../ch10/ch10-02.html">
            
                    
                    导入路径
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.11.3" data-path="../ch10/ch10-03.html">
            
                <a href="../ch10/ch10-03.html">
            
                    
                    包声明
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.11.4" data-path="../ch10/ch10-04.html">
            
                <a href="../ch10/ch10-04.html">
            
                    
                    导入声明
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.11.5" data-path="../ch10/ch10-05.html">
            
                <a href="../ch10/ch10-05.html">
            
                    
                    包的匿名导入
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.11.6" data-path="../ch10/ch10-06.html">
            
                <a href="../ch10/ch10-06.html">
            
                    
                    包和命名
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.11.7" data-path="../ch10/ch10-07.html">
            
                <a href="../ch10/ch10-07.html">
            
                    
                    工具
            
                </a>
            

            
        </li>
    

            </ul>
            
        </li>
    
        <li class="chapter " data-level="1.12" data-path="../ch11/ch11.html">
            
                <a href="../ch11/ch11.html">
            
                    
                    测试
            
                </a>
            

            
            <ul class="articles">
                
    
        <li class="chapter " data-level="1.12.1" data-path="../ch11/ch11-01.html">
            
                <a href="../ch11/ch11-01.html">
            
                    
                    go test
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.12.2" data-path="../ch11/ch11-02.html">
            
                <a href="../ch11/ch11-02.html">
            
                    
                    测试函数
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.12.3" data-path="../ch11/ch11-03.html">
            
                <a href="../ch11/ch11-03.html">
            
                    
                    测试覆盖率
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.12.4" data-path="../ch11/ch11-04.html">
            
                <a href="../ch11/ch11-04.html">
            
                    
                    基准测试
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.12.5" data-path="../ch11/ch11-05.html">
            
                <a href="../ch11/ch11-05.html">
            
                    
                    剖析
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.12.6" data-path="../ch11/ch11-06.html">
            
                <a href="../ch11/ch11-06.html">
            
                    
                    示例函数
            
                </a>
            

            
        </li>
    

            </ul>
            
        </li>
    
        <li class="chapter " data-level="1.13" data-path="ch12.html">
            
                <a href="ch12.html">
            
                    
                    反射
            
                </a>
            

            
            <ul class="articles">
                
    
        <li class="chapter " data-level="1.13.1" data-path="ch12-01.html">
            
                <a href="ch12-01.html">
            
                    
                    为何需要反射?
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.13.2" data-path="ch12-02.html">
            
                <a href="ch12-02.html">
            
                    
                    reflect.Type和reflect.Value
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.13.3" data-path="ch12-03.html">
            
                <a href="ch12-03.html">
            
                    
                    Display递归打印
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.13.4" data-path="ch12-04.html">
            
                <a href="ch12-04.html">
            
                    
                    示例: 编码S表达式
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.13.5" data-path="ch12-05.html">
            
                <a href="ch12-05.html">
            
                    
                    通过reflect.Value修改值
            
                </a>
            

            
        </li>
    
        <li class="chapter active" data-level="1.13.6" data-path="ch12-06.html">
            
                <a href="ch12-06.html">
            
                    
                    示例: 解码S表达式
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.13.7" data-path="ch12-07.html">
            
                <a href="ch12-07.html">
            
                    
                    获取结构体字段标签
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.13.8" data-path="ch12-08.html">
            
                <a href="ch12-08.html">
            
                    
                    显示一个类型的方法集
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.13.9" data-path="ch12-09.html">
            
                <a href="ch12-09.html">
            
                    
                    几点忠告
            
                </a>
            

            
        </li>
    

            </ul>
            
        </li>
    
        <li class="chapter " data-level="1.14" data-path="../ch13/ch13.html">
            
                <a href="../ch13/ch13.html">
            
                    
                    底层编程
            
                </a>
            

            
            <ul class="articles">
                
    
        <li class="chapter " data-level="1.14.1" data-path="../ch13/ch13-01.html">
            
                <a href="../ch13/ch13-01.html">
            
                    
                    unsafe.Sizeof, Alignof 和 Offsetof
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.14.2" data-path="../ch13/ch13-02.html">
            
                <a href="../ch13/ch13-02.html">
            
                    
                    unsafe.Pointer
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.14.3" data-path="../ch13/ch13-03.html">
            
                <a href="../ch13/ch13-03.html">
            
                    
                    示例: 深度相等判断
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.14.4" data-path="../ch13/ch13-04.html">
            
                <a href="../ch13/ch13-04.html">
            
                    
                    通过cgo调用C代码
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.14.5" data-path="../ch13/ch13-05.html">
            
                <a href="../ch13/ch13-05.html">
            
                    
                    几点忠告
            
                </a>
            

            
        </li>
    

            </ul>
            
        </li>
    
        <li class="chapter " data-level="1.15" data-path="../appendix/appendix.html">
            
                <a href="../appendix/appendix.html">
            
                    
                    附录
            
                </a>
            

            
            <ul class="articles">
                
    
        <li class="chapter " data-level="1.15.1" data-path="../appendix/appendix-a-errata.html">
            
                <a href="../appendix/appendix-a-errata.html">
            
                    
                    附录A：原文勘误
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.15.2" data-path="../appendix/appendix-b-author.html">
            
                <a href="../appendix/appendix-b-author.html">
            
                    
                    附录B：作者译者
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.15.3" data-path="../appendix/appendix-c-cpoyright.html">
            
                <a href="../appendix/appendix-c-cpoyright.html">
            
                    
                    附录C：译文授权
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.15.4" data-path="../appendix/appendix-d-translations.html">
            
                <a href="../appendix/appendix-d-translations.html">
            
                    
                    附录D：其它语言
            
                </a>
            

            
        </li>
    

            </ul>
            
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        <a href=".." >示例: 解码S表达式</a>
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                                <h2 id="126-&#x793A;&#x4F8B;-&#x89E3;&#x7801;s&#x8868;&#x8FBE;&#x5F0F;">12.6. &#x793A;&#x4F8B;: &#x89E3;&#x7801;S&#x8868;&#x8FBE;&#x5F0F;</h2>
<p>&#x6807;&#x51C6;&#x5E93;&#x4E2D;encoding/...&#x4E0B;&#x6BCF;&#x4E2A;&#x5305;&#x4E2D;&#x63D0;&#x4F9B;&#x7684;Marshal&#x7F16;&#x7801;&#x51FD;&#x6570;&#x90FD;&#x6709;&#x4E00;&#x4E2A;&#x5BF9;&#x5E94;&#x7684;Unmarshal&#x51FD;&#x6570;&#x7528;&#x4E8E;&#x89E3;&#x7801;&#x3002;&#x4F8B;&#x5982;&#xFF0C;&#x6211;&#x4EEC;&#x5728;4.5&#x8282;&#x4E2D;&#x770B;&#x5230;&#x7684;&#xFF0C;&#x8981;&#x5C06;&#x5305;&#x542B;JSON&#x7F16;&#x7801;&#x683C;&#x5F0F;&#x7684;&#x5B57;&#x8282;slice&#x6570;&#x636E;&#x89E3;&#x7801;&#x4E3A;&#x6211;&#x4EEC;&#x81EA;&#x5DF1;&#x7684;Movie&#x7C7B;&#x578B;&#xFF08;&#xA7;12.3&#xFF09;&#xFF0C;&#x6211;&#x4EEC;&#x53EF;&#x4EE5;&#x8FD9;&#x6837;&#x505A;&#xFF1A;</p>
<pre><code class="lang-Go">data := []<span class="hljs-keyword">byte</span>{<span class="hljs-comment">/* ... */</span>}
<span class="hljs-keyword">var</span> movie Movie
err := json.Unmarshal(data, &amp;movie)
</code></pre>
<p>Unmarshal&#x51FD;&#x6570;&#x4F7F;&#x7528;&#x4E86;&#x53CD;&#x5C04;&#x673A;&#x5236;&#x7C7B;&#x4FEE;&#x6539;movie&#x53D8;&#x91CF;&#x7684;&#x6BCF;&#x4E2A;&#x6210;&#x5458;&#xFF0C;&#x6839;&#x636E;&#x8F93;&#x5165;&#x7684;&#x5185;&#x5BB9;&#x4E3A;Movie&#x6210;&#x5458;&#x521B;&#x5EFA;&#x5BF9;&#x5E94;&#x7684;map&#x3001;&#x7ED3;&#x6784;&#x4F53;&#x548C;slice&#x3002;</p>
<p>&#x73B0;&#x5728;&#x8BA9;&#x6211;&#x4EEC;&#x4E3A;S&#x8868;&#x8FBE;&#x5F0F;&#x7F16;&#x7801;&#x5B9E;&#x73B0;&#x4E00;&#x4E2A;&#x7B80;&#x6613;&#x7684;Unmarshal&#xFF0C;&#x7C7B;&#x4F3C;&#x4E8E;&#x524D;&#x9762;&#x7684;json.Unmarshal&#x6807;&#x51C6;&#x5E93;&#x51FD;&#x6570;&#xFF0C;&#x5BF9;&#x5E94;&#x6211;&#x4EEC;&#x4E4B;&#x524D;&#x5B9E;&#x73B0;&#x7684;sexpr.Marshal&#x51FD;&#x6570;&#x7684;&#x9006;&#x64CD;&#x4F5C;&#x3002;&#x6211;&#x4EEC;&#x5FC5;&#x987B;&#x63D0;&#x9192;&#x4E00;&#x4E0B;&#xFF0C;&#x4E00;&#x4E2A;&#x5065;&#x58EE;&#x7684;&#x548C;&#x901A;&#x7528;&#x7684;&#x5B9E;&#x73B0;&#x901A;&#x5E38;&#x9700;&#x8981;&#x6BD4;&#x4F8B;&#x5B50;&#x66F4;&#x591A;&#x7684;&#x4EE3;&#x7801;&#xFF0C;&#x4E3A;&#x4E86;&#x4FBF;&#x4E8E;&#x6F14;&#x793A;&#x6211;&#x4EEC;&#x91C7;&#x7528;&#x4E86;&#x7CBE;&#x7B80;&#x7684;&#x5B9E;&#x73B0;&#x3002;&#x6211;&#x4EEC;&#x53EA;&#x652F;&#x6301;S&#x8868;&#x8FBE;&#x5F0F;&#x6709;&#x9650;&#x7684;&#x5B50;&#x96C6;&#xFF0C;&#x540C;&#x65F6;&#x5904;&#x7406;&#x9519;&#x8BEF;&#x7684;&#x65B9;&#x5F0F;&#x4E5F;&#x6BD4;&#x8F83;&#x7C97;&#x66B4;&#xFF0C;&#x4EE3;&#x7801;&#x7684;&#x76EE;&#x7684;&#x662F;&#x4E3A;&#x4E86;&#x6F14;&#x793A;&#x53CD;&#x5C04;&#x7684;&#x7528;&#x6CD5;&#xFF0C;&#x800C;&#x4E0D;&#x662F;&#x6784;&#x9020;&#x4E00;&#x4E2A;&#x5B9E;&#x7528;&#x7684;S&#x8868;&#x8FBE;&#x5F0F;&#x7684;&#x89E3;&#x7801;&#x5668;&#x3002;</p>
<p>&#x8BCD;&#x6CD5;&#x5206;&#x6790;&#x5668;lexer&#x4F7F;&#x7528;&#x4E86;&#x6807;&#x51C6;&#x5E93;&#x4E2D;&#x7684;text/scanner&#x5305;&#x5C06;&#x8F93;&#x5165;&#x6D41;&#x7684;&#x5B57;&#x8282;&#x6570;&#x636E;&#x89E3;&#x6790;&#x4E3A;&#x4E00;&#x4E2A;&#x4E2A;&#x7C7B;&#x4F3C;&#x6CE8;&#x91CA;&#x3001;&#x6807;&#x8BC6;&#x7B26;&#x3001;&#x5B57;&#x7B26;&#x4E32;&#x9762;&#x503C;&#x548C;&#x6570;&#x5B57;&#x9762;&#x503C;&#x4E4B;&#x7C7B;&#x7684;&#x6807;&#x8BB0;&#x3002;&#x8F93;&#x5165;&#x626B;&#x63CF;&#x5668;scanner&#x7684;Scan&#x65B9;&#x6CD5;&#x5C06;&#x63D0;&#x524D;&#x626B;&#x63CF;&#x548C;&#x8FD4;&#x56DE;&#x4E0B;&#x4E00;&#x4E2A;&#x8BB0;&#x53F7;&#xFF0C;&#x5BF9;&#x4E8E;rune&#x7C7B;&#x578B;&#x3002;&#x5927;&#x591A;&#x6570;&#x8BB0;&#x53F7;&#xFF0C;&#x6BD4;&#x5982;&#x201C;(&#x201D;&#xFF0C;&#x5BF9;&#x5E94;&#x4E00;&#x4E2A;&#x5355;&#x4E00;rune&#x53EF;&#x8868;&#x793A;&#x7684;Unicode&#x5B57;&#x7B26;&#xFF0C;&#x4F46;&#x662F;text/scanner&#x4E5F;&#x53EF;&#x4EE5;&#x7528;&#x5C0F;&#x7684;&#x8D1F;&#x6570;&#x8868;&#x793A;&#x8BB0;&#x53F7;&#x6807;&#x8BC6;&#x7B26;&#x3001;&#x5B57;&#x7B26;&#x4E32;&#x7B49;&#x7531;&#x591A;&#x4E2A;&#x5B57;&#x7B26;&#x7EC4;&#x6210;&#x7684;&#x8BB0;&#x53F7;&#x3002;&#x8C03;&#x7528;Scan&#x65B9;&#x6CD5;&#x5C06;&#x8FD4;&#x56DE;&#x8FD9;&#x4E9B;&#x8BB0;&#x53F7;&#x7684;&#x7C7B;&#x578B;&#xFF0C;&#x63A5;&#x7740;&#x8C03;&#x7528;TokenText&#x65B9;&#x6CD5;&#x5C06;&#x8FD4;&#x56DE;&#x8BB0;&#x53F7;&#x5BF9;&#x5E94;&#x7684;&#x6587;&#x672C;&#x5185;&#x5BB9;&#x3002;</p>
<p>&#x56E0;&#x4E3A;&#x6BCF;&#x4E2A;&#x89E3;&#x6790;&#x5668;&#x53EF;&#x80FD;&#x9700;&#x8981;&#x591A;&#x6B21;&#x4F7F;&#x7528;&#x5F53;&#x524D;&#x7684;&#x8BB0;&#x53F7;&#xFF0C;&#x4F46;&#x662F;Scan&#x4F1A;&#x4E00;&#x76F4;&#x5411;&#x524D;&#x626B;&#x63CF;&#xFF0C;&#x6240;&#x4EE5;&#x6211;&#x4EEC;&#x5305;&#x88C5;&#x4E86;&#x4E00;&#x4E2A;lexer&#x626B;&#x63CF;&#x5668;&#x8F85;&#x52A9;&#x7C7B;&#x578B;&#xFF0C;&#x7528;&#x4E8E;&#x8DDF;&#x8E2A;&#x6700;&#x8FD1;&#x7531;Scan&#x65B9;&#x6CD5;&#x8FD4;&#x56DE;&#x7684;&#x8BB0;&#x53F7;&#x3002;</p>
<p><u><i>gopl.io/ch12/sexpr</i></u></p>
<pre><code class="lang-Go"><span class="hljs-keyword">type</span> lexer <span class="hljs-keyword">struct</span> {
    scan  scanner.Scanner
    token <span class="hljs-keyword">rune</span> <span class="hljs-comment">// the current token</span>
}

<span class="hljs-keyword">func</span> (lex *lexer) next()        { lex.token = lex.scan.Scan() }
<span class="hljs-keyword">func</span> (lex *lexer) text() <span class="hljs-keyword">string</span> { <span class="hljs-keyword">return</span> lex.scan.TokenText() }

<span class="hljs-keyword">func</span> (lex *lexer) consume(want <span class="hljs-keyword">rune</span>) {
    <span class="hljs-keyword">if</span> lex.token != want { <span class="hljs-comment">// <span class="hljs-doctag">NOTE:</span> Not an example of good error handling.</span>
        <span class="hljs-built_in">panic</span>(fmt.Sprintf(<span class="hljs-string">&quot;got %q, want %q&quot;</span>, lex.text(), want))
    }
    lex.next()
}
</code></pre>
<p>&#x73B0;&#x5728;&#x8BA9;&#x6211;&#x4EEC;&#x8F6C;&#x5230;&#x8BED;&#x6CD5;&#x89E3;&#x6790;&#x5668;&#x3002;&#x5B83;&#x4E3B;&#x8981;&#x5305;&#x542B;&#x4E24;&#x4E2A;&#x529F;&#x80FD;&#x3002;&#x7B2C;&#x4E00;&#x4E2A;&#x662F;read&#x51FD;&#x6570;&#xFF0C;&#x7528;&#x4E8E;&#x8BFB;&#x53D6;S&#x8868;&#x8FBE;&#x5F0F;&#x7684;&#x5F53;&#x524D;&#x6807;&#x8BB0;&#xFF0C;&#x7136;&#x540E;&#x6839;&#x636E;S&#x8868;&#x8FBE;&#x5F0F;&#x7684;&#x5F53;&#x524D;&#x6807;&#x8BB0;&#x66F4;&#x65B0;&#x53EF;&#x53D6;&#x5730;&#x5740;&#x7684;reflect.Value&#x5BF9;&#x5E94;&#x7684;&#x53D8;&#x91CF;v&#x3002;</p>
<pre><code class="lang-Go"><span class="hljs-keyword">func</span> read(lex *lexer, v reflect.Value) {
    <span class="hljs-keyword">switch</span> lex.token {
    <span class="hljs-keyword">case</span> scanner.Ident:
        <span class="hljs-comment">// The only valid identifiers are</span>
        <span class="hljs-comment">// &quot;nil&quot; and struct field names.</span>
        <span class="hljs-keyword">if</span> lex.text() == <span class="hljs-string">&quot;nil&quot;</span> {
            v.Set(reflect.Zero(v.Type()))
            lex.next()
            <span class="hljs-keyword">return</span>
        }
    <span class="hljs-keyword">case</span> scanner.String:
        s, _ := strconv.Unquote(lex.text()) <span class="hljs-comment">// <span class="hljs-doctag">NOTE:</span> ignoring errors</span>
        v.SetString(s)
        lex.next()
        <span class="hljs-keyword">return</span>
    <span class="hljs-keyword">case</span> scanner.Int:
        i, _ := strconv.Atoi(lex.text()) <span class="hljs-comment">// <span class="hljs-doctag">NOTE:</span> ignoring errors</span>
        v.SetInt(<span class="hljs-keyword">int64</span>(i))
        lex.next()
        <span class="hljs-keyword">return</span>
    <span class="hljs-keyword">case</span> <span class="hljs-string">&apos;(&apos;</span>:
        lex.next()
        readList(lex, v)
        lex.next() <span class="hljs-comment">// consume &apos;)&apos;</span>
        <span class="hljs-keyword">return</span>
    }
    <span class="hljs-built_in">panic</span>(fmt.Sprintf(<span class="hljs-string">&quot;unexpected token %q&quot;</span>, lex.text()))
}
</code></pre>
<p>&#x6211;&#x4EEC;&#x7684;S&#x8868;&#x8FBE;&#x5F0F;&#x4F7F;&#x7528;&#x6807;&#x8BC6;&#x7B26;&#x533A;&#x5206;&#x4E24;&#x4E2A;&#x4E0D;&#x540C;&#x7C7B;&#x578B;&#xFF0C;&#x7ED3;&#x6784;&#x4F53;&#x6210;&#x5458;&#x540D;&#x548C;nil&#x503C;&#x7684;&#x6307;&#x9488;&#x3002;read&#x51FD;&#x6570;&#x503C;&#x5904;&#x7406;nil&#x7C7B;&#x578B;&#x7684;&#x6807;&#x8BC6;&#x7B26;&#x3002;&#x5F53;&#x9047;&#x5230;scanner.Ident&#x4E3A;&#x201C;nil&#x201D;&#x662F;&#xFF0C;&#x4F7F;&#x7528;reflect.Zero&#x51FD;&#x6570;&#x5C06;&#x53D8;&#x91CF;v&#x8BBE;&#x7F6E;&#x4E3A;&#x96F6;&#x503C;&#x3002;&#x800C;&#x5176;&#x5B83;&#x4EFB;&#x4F55;&#x7C7B;&#x578B;&#x7684;&#x6807;&#x8BC6;&#x7B26;&#xFF0C;&#x6211;&#x4EEC;&#x90FD;&#x4F5C;&#x4E3A;&#x9519;&#x8BEF;&#x5904;&#x7406;&#x3002;&#x540E;&#x9762;&#x7684;readList&#x51FD;&#x6570;&#x5C06;&#x5904;&#x7406;&#x7ED3;&#x6784;&#x4F53;&#x7684;&#x6210;&#x5458;&#x540D;&#x3002;</p>
<p>&#x4E00;&#x4E2A;&#x201C;(&#x201D;&#x6807;&#x8BB0;&#x5BF9;&#x5E94;&#x4E00;&#x4E2A;&#x5217;&#x8868;&#x7684;&#x5F00;&#x59CB;&#x3002;&#x7B2C;&#x4E8C;&#x4E2A;&#x51FD;&#x6570;readList&#xFF0C;&#x5C06;&#x4E00;&#x4E2A;&#x5217;&#x8868;&#x89E3;&#x7801;&#x5230;&#x4E00;&#x4E2A;&#x805A;&#x5408;&#x7C7B;&#x578B;&#x4E2D;&#xFF08;map&#x3001;&#x7ED3;&#x6784;&#x4F53;&#x3001;slice&#x6216;&#x6570;&#x7EC4;&#xFF09;&#xFF0C;&#x5177;&#x4F53;&#x7C7B;&#x578B;&#x4F9D;&#x7136;&#x4E8E;&#x4F20;&#x5165;&#x5F85;&#x586B;&#x5145;&#x53D8;&#x91CF;&#x7684;&#x7C7B;&#x578B;&#x3002;&#x6BCF;&#x6B21;&#x9047;&#x5230;&#x8FD9;&#x79CD;&#x60C5;&#x51B5;&#xFF0C;&#x5FAA;&#x73AF;&#x7EE7;&#x7EED;&#x89E3;&#x6790;&#x6BCF;&#x4E2A;&#x5143;&#x7D20;&#x76F4;&#x5230;&#x9047;&#x5230;&#x4E8E;&#x5F00;&#x59CB;&#x6807;&#x8BB0;&#x5339;&#x914D;&#x7684;&#x7ED3;&#x675F;&#x6807;&#x8BB0;&#x201C;)&#x201D;&#xFF0C;endList&#x51FD;&#x6570;&#x7528;&#x4E8E;&#x68C0;&#x6D4B;&#x7ED3;&#x675F;&#x6807;&#x8BB0;&#x3002;</p>
<p>&#x6700;&#x6709;&#x8DA3;&#x7684;&#x90E8;&#x5206;&#x662F;&#x9012;&#x5F52;&#x3002;&#x6700;&#x7B80;&#x5355;&#x7684;&#x662F;&#x5BF9;&#x6570;&#x7EC4;&#x7C7B;&#x578B;&#x7684;&#x5904;&#x7406;&#x3002;&#x76F4;&#x5230;&#x9047;&#x5230;&#x201C;)&#x201D;&#x7ED3;&#x675F;&#x6807;&#x8BB0;&#xFF0C;&#x6211;&#x4EEC;&#x4F7F;&#x7528;Index&#x51FD;&#x6570;&#x6765;&#x83B7;&#x53D6;&#x6570;&#x7EC4;&#x6BCF;&#x4E2A;&#x5143;&#x7D20;&#x7684;&#x5730;&#x5740;&#xFF0C;&#x7136;&#x540E;&#x9012;&#x5F52;&#x8C03;&#x7528;read&#x51FD;&#x6570;&#x5904;&#x7406;&#x3002;&#x548C;&#x5176;&#x5B83;&#x9519;&#x8BEF;&#x7C7B;&#x4F3C;&#xFF0C;&#x5982;&#x679C;&#x8F93;&#x5165;&#x6570;&#x636E;&#x5BFC;&#x81F4;&#x89E3;&#x7801;&#x5668;&#x7684;&#x5F15;&#x7528;&#x8D85;&#x51FA;&#x4E86;&#x6570;&#x7EC4;&#x7684;&#x8303;&#x56F4;&#xFF0C;&#x89E3;&#x7801;&#x5668;&#x5C06;&#x629B;&#x51FA;panic&#x5F02;&#x5E38;&#x3002;slice&#x4E5F;&#x91C7;&#x7528;&#x7C7B;&#x4F3C;&#x65B9;&#x6CD5;&#x89E3;&#x6790;&#xFF0C;&#x4E0D;&#x540C;&#x7684;&#x662F;&#x6211;&#x4EEC;&#x5C06;&#x4E3A;&#x6BCF;&#x4E2A;&#x5143;&#x7D20;&#x521B;&#x5EFA;&#x65B0;&#x7684;&#x53D8;&#x91CF;&#xFF0C;&#x7136;&#x540E;&#x5C06;&#x5143;&#x7D20;&#x6DFB;&#x52A0;&#x5230;slice&#x7684;&#x672B;&#x5C3E;&#x3002;</p>
<p>&#x5728;&#x5FAA;&#x73AF;&#x5904;&#x7406;&#x7ED3;&#x6784;&#x4F53;&#x548C;map&#x6BCF;&#x4E2A;&#x5143;&#x7D20;&#x65F6;&#x5FC5;&#x987B;&#x89E3;&#x7801;&#x4E00;&#x4E2A;(key value)&#x683C;&#x5F0F;&#x7684;&#x5BF9;&#x5E94;&#x5B50;&#x5217;&#x8868;&#x3002;&#x5BF9;&#x4E8E;&#x7ED3;&#x6784;&#x4F53;&#xFF0C;key&#x90E8;&#x5206;&#x5BF9;&#x4E8E;&#x6210;&#x5458;&#x7684;&#x540D;&#x5B57;&#x3002;&#x548C;&#x6570;&#x7EC4;&#x7C7B;&#x4F3C;&#xFF0C;&#x6211;&#x4EEC;&#x4F7F;&#x7528;FieldByName&#x627E;&#x5230;&#x7ED3;&#x6784;&#x4F53;&#x5BF9;&#x5E94;&#x6210;&#x5458;&#x7684;&#x53D8;&#x91CF;&#xFF0C;&#x7136;&#x540E;&#x9012;&#x5F52;&#x8C03;&#x7528;read&#x51FD;&#x6570;&#x5904;&#x7406;&#x3002;&#x5BF9;&#x4E8E;map&#xFF0C;key&#x53EF;&#x80FD;&#x662F;&#x4EFB;&#x610F;&#x7C7B;&#x578B;&#xFF0C;&#x5BF9;&#x5143;&#x7D20;&#x7684;&#x5904;&#x7406;&#x65B9;&#x5F0F;&#x548C;slice&#x7C7B;&#x4F3C;&#xFF0C;&#x6211;&#x4EEC;&#x521B;&#x5EFA;&#x4E00;&#x4E2A;&#x65B0;&#x7684;&#x53D8;&#x91CF;&#xFF0C;&#x7136;&#x540E;&#x9012;&#x5F52;&#x586B;&#x5145;&#x5B83;&#xFF0C;&#x6700;&#x540E;&#x5C06;&#x65B0;&#x89E3;&#x6790;&#x5230;&#x7684;key/value&#x5BF9;&#x6DFB;&#x52A0;&#x5230;map&#x3002;</p>
<pre><code class="lang-Go"><span class="hljs-keyword">func</span> readList(lex *lexer, v reflect.Value) {
    <span class="hljs-keyword">switch</span> v.Kind() {
    <span class="hljs-keyword">case</span> reflect.Array: <span class="hljs-comment">// (item ...)</span>
        <span class="hljs-keyword">for</span> i := <span class="hljs-number">0</span>; !endList(lex); i++ {
            read(lex, v.Index(i))
        }

    <span class="hljs-keyword">case</span> reflect.Slice: <span class="hljs-comment">// (item ...)</span>
        <span class="hljs-keyword">for</span> !endList(lex) {
            item := reflect.New(v.Type().Elem()).Elem()
            read(lex, item)
            v.Set(reflect.Append(v, item))
        }

    <span class="hljs-keyword">case</span> reflect.Struct: <span class="hljs-comment">// ((name value) ...)</span>
        <span class="hljs-keyword">for</span> !endList(lex) {
            lex.consume(<span class="hljs-string">&apos;(&apos;</span>)
            <span class="hljs-keyword">if</span> lex.token != scanner.Ident {
                <span class="hljs-built_in">panic</span>(fmt.Sprintf(<span class="hljs-string">&quot;got token %q, want field name&quot;</span>, lex.text()))
            }
            name := lex.text()
            lex.next()
            read(lex, v.FieldByName(name))
            lex.consume(<span class="hljs-string">&apos;)&apos;</span>)
        }

    <span class="hljs-keyword">case</span> reflect.Map: <span class="hljs-comment">// ((key value) ...)</span>
        v.Set(reflect.MakeMap(v.Type()))
        <span class="hljs-keyword">for</span> !endList(lex) {
            lex.consume(<span class="hljs-string">&apos;(&apos;</span>)
            key := reflect.New(v.Type().Key()).Elem()
            read(lex, key)
            value := reflect.New(v.Type().Elem()).Elem()
            read(lex, value)
            v.SetMapIndex(key, value)
            lex.consume(<span class="hljs-string">&apos;)&apos;</span>)
        }

    <span class="hljs-keyword">default</span>:
        <span class="hljs-built_in">panic</span>(fmt.Sprintf(<span class="hljs-string">&quot;cannot decode list into %v&quot;</span>, v.Type()))
    }
}

<span class="hljs-keyword">func</span> endList(lex *lexer) <span class="hljs-keyword">bool</span> {
    <span class="hljs-keyword">switch</span> lex.token {
    <span class="hljs-keyword">case</span> scanner.EOF:
        <span class="hljs-built_in">panic</span>(<span class="hljs-string">&quot;end of file&quot;</span>)
    <span class="hljs-keyword">case</span> <span class="hljs-string">&apos;)&apos;</span>:
        <span class="hljs-keyword">return</span> <span class="hljs-literal">true</span>
    }
    <span class="hljs-keyword">return</span> <span class="hljs-literal">false</span>
}
</code></pre>
<p>&#x6700;&#x540E;&#xFF0C;&#x6211;&#x4EEC;&#x5C06;&#x89E3;&#x6790;&#x5668;&#x5305;&#x88C5;&#x4E3A;&#x5BFC;&#x51FA;&#x7684;Unmarshal&#x89E3;&#x7801;&#x51FD;&#x6570;&#xFF0C;&#x9690;&#x85CF;&#x4E86;&#x4E00;&#x4E9B;&#x521D;&#x59CB;&#x5316;&#x548C;&#x6E05;&#x7406;&#x7B49;&#x8FB9;&#x7F18;&#x5904;&#x7406;&#x3002;&#x5185;&#x90E8;&#x89E3;&#x6790;&#x5668;&#x4EE5;panic&#x7684;&#x65B9;&#x5F0F;&#x629B;&#x51FA;&#x9519;&#x8BEF;&#xFF0C;&#x4F46;&#x662F;Unmarshal&#x51FD;&#x6570;&#x901A;&#x8FC7;&#x5728;defer&#x8BED;&#x53E5;&#x8C03;&#x7528;recover&#x51FD;&#x6570;&#x6765;&#x6355;&#x83B7;&#x5185;&#x90E8;panic&#xFF08;&#xA7;5.10&#xFF09;&#xFF0C;&#x7136;&#x540E;&#x8FD4;&#x56DE;&#x4E00;&#x4E2A;&#x5BF9;panic&#x5BF9;&#x5E94;&#x7684;&#x9519;&#x8BEF;&#x4FE1;&#x606F;&#x3002;</p>
<pre><code class="lang-Go"><span class="hljs-comment">// Unmarshal parses S-expression data and populates the variable</span>
<span class="hljs-comment">// whose address is in the non-nil pointer out.</span>
<span class="hljs-keyword">func</span> Unmarshal(data []<span class="hljs-keyword">byte</span>, out <span class="hljs-keyword">interface</span>{}) (err error) {
    lex := &amp;lexer{scan: scanner.Scanner{Mode: scanner.GoTokens}}
    lex.scan.Init(bytes.NewReader(data))
    lex.next() <span class="hljs-comment">// get the first token</span>
    <span class="hljs-keyword">defer</span> <span class="hljs-keyword">func</span>() {
        <span class="hljs-comment">// <span class="hljs-doctag">NOTE:</span> this is not an example of ideal error handling.</span>
        <span class="hljs-keyword">if</span> x := <span class="hljs-built_in">recover</span>(); x != <span class="hljs-literal">nil</span> {
            err = fmt.Errorf(<span class="hljs-string">&quot;error at %s: %v&quot;</span>, lex.scan.Position, x)
        }
    }()
    read(lex, reflect.ValueOf(out).Elem())
    <span class="hljs-keyword">return</span> <span class="hljs-literal">nil</span>
}
</code></pre>
<p>&#x751F;&#x4EA7;&#x5B9E;&#x73B0;&#x4E0D;&#x5E94;&#x8BE5;&#x5BF9;&#x4EFB;&#x4F55;&#x8F93;&#x5165;&#x95EE;&#x9898;&#x90FD;&#x7528;panic&#x5F62;&#x5F0F;&#x62A5;&#x544A;&#xFF0C;&#x800C;&#x4E14;&#x5E94;&#x8BE5;&#x62A5;&#x544A;&#x4E00;&#x4E9B;&#x9519;&#x8BEF;&#x76F8;&#x5173;&#x7684;&#x4FE1;&#x606F;&#xFF0C;&#x4F8B;&#x5982;&#x51FA;&#x73B0;&#x9519;&#x8BEF;&#x8F93;&#x5165;&#x7684;&#x884C;&#x53F7;&#x548C;&#x4F4D;&#x7F6E;&#x7B49;&#x3002;&#x5C3D;&#x7BA1;&#x5982;&#x6B64;&#xFF0C;&#x6211;&#x4EEC;&#x5E0C;&#x671B;&#x901A;&#x8FC7;&#x8FD9;&#x4E2A;&#x4F8B;&#x5B50;&#x6765;&#x5C55;&#x793A;&#x7C7B;&#x4F3C;encoding/json&#x7B49;&#x5305;&#x5E95;&#x5C42;&#x4EE3;&#x7801;&#x7684;&#x5B9E;&#x73B0;&#x601D;&#x8DEF;&#xFF0C;&#x4EE5;&#x53CA;&#x5982;&#x4F55;&#x4F7F;&#x7528;&#x53CD;&#x5C04;&#x673A;&#x5236;&#x6765;&#x586B;&#x5145;&#x6570;&#x636E;&#x7ED3;&#x6784;&#x3002;</p>
<p><strong>&#x7EC3;&#x4E60; 12.8&#xFF1A;</strong> sexpr.Unmarshal&#x51FD;&#x6570;&#x548C;json.Unmarshal&#x4E00;&#x6837;&#xFF0C;&#x90FD;&#x8981;&#x6C42;&#x5728;&#x89E3;&#x7801;&#x524D;&#x8F93;&#x5165;&#x5B8C;&#x6574;&#x7684;&#x5B57;&#x8282;slice&#x3002;&#x5B9A;&#x4E49;&#x4E00;&#x4E2A;&#x548C;json.Decoder&#x7C7B;&#x4F3C;&#x7684;sexpr.Decoder&#x7C7B;&#x578B;&#xFF0C;&#x652F;&#x6301;&#x4ECE;&#x4E00;&#x4E2A;io.Reader&#x6D41;&#x89E3;&#x7801;&#x3002;&#x4FEE;&#x6539;sexpr.Unmarshal&#x51FD;&#x6570;&#xFF0C;&#x4F7F;&#x7528;&#x8FD9;&#x4E2A;&#x65B0;&#x7684;&#x7C7B;&#x578B;&#x5B9E;&#x73B0;&#x3002;</p>
<p><strong>&#x7EC3;&#x4E60; 12.9&#xFF1A;</strong> &#x7F16;&#x5199;&#x4E00;&#x4E2A;&#x57FA;&#x4E8E;&#x6807;&#x8BB0;&#x7684;API&#x7528;&#x4E8E;&#x89E3;&#x7801;S&#x8868;&#x8FBE;&#x5F0F;&#xFF0C;&#x53C2;&#x8003;xml.Decoder&#xFF08;7.14&#xFF09;&#x7684;&#x98CE;&#x683C;&#x3002;&#x4F60;&#x5C06;&#x9700;&#x8981;&#x4E94;&#x79CD;&#x7C7B;&#x578B;&#x7684;&#x6807;&#x8BB0;&#xFF1A;Symbol&#x3001;String&#x3001;Int&#x3001;StartList&#x548C;EndList&#x3002;</p>
<p><strong>&#x7EC3;&#x4E60; 12.10&#xFF1A;</strong> &#x6269;&#x5C55;sexpr.Unmarshal&#x51FD;&#x6570;&#xFF0C;&#x652F;&#x6301;&#x5E03;&#x5C14;&#x578B;&#x3001;&#x6D6E;&#x70B9;&#x6570;&#x548C;interface&#x7C7B;&#x578B;&#x7684;&#x89E3;&#x7801;&#xFF0C;&#x4F7F;&#x7528; <strong>&#x7EC3;&#x4E60; 12.3&#xFF1A;</strong> &#x7684;&#x65B9;&#x6848;&#x3002;&#xFF08;&#x63D0;&#x793A;&#xFF1A;&#x8981;&#x89E3;&#x7801;&#x63A5;&#x53E3;&#xFF0C;&#x4F60;&#x9700;&#x8981;&#x5C06;name&#x6620;&#x5C04;&#x5230;&#x6BCF;&#x4E2A;&#x652F;&#x6301;&#x7C7B;&#x578B;&#x7684;reflect.Type&#x3002;&#xFF09;</p>

                                
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